The present invention relates to a thermal transfer recording apparatus (e.g., a thermal transfer printer) and a thermal transfer recording method (e.g., a thermal transfer printing method). In particular, the present invention relates to a thermal transfer recording apparatus and a thermal transfer recording method in which a full-colored and high quality image can be formed on a plain paper at a high speed and a low cost, for example, in a digital mode.
A thermal transfer recording method in which a dye is transferred by heating can provide an image having a high quality which is substantially equivalent to that of the silver halide conventional full color photograph. Furthermore, the thermal transfer recording method is an excellent recording technique which puts less of a load on the global environment and which allows instant recording (or printing) (i.e., recording can be done immediately). An apparatus for such a method is compact and excellent in its maintainability.
However, it is necessary to use a substrate as an image receiver comprising pulp paper, both surfaces of which are laminated with a formed polyester (PET) film, etc. in order to reproduce a high quality image. Therefore, the thermal transfer recording method has a disadvantage in that the substrate, which is expensive, is to be used as the image receiver, and no other substrate can be selected. This means a lower degree of freedom as to the substrate selection. Several thermal transfer recording methods which are called re-transfer recording methods have been proposed in order to solve such a problem.
The first re-transfer recording method is a method wherein an image is recorded (i.e., printed) by thermal transfer of a dye on a dye receiving layer supporting sheet (a sheet which carries a dye receiving layer) which is obtained by forming the dye receiving layer (a layer on which the image is to be recorded (or printed)) on a thin sheet-form substrate such as a PET film with a method such as a coating method, and the dye receiving layer on which the image has been formed (or recorded) is re-transferred to a (final) image receiver such as paper (see, for example, Japanese Patent Kokai Publication No.63-81093). However, the dye receiving layer supporting sheet is made of the thin sheet-form substrate and the image is formed on the dye receiving layer on such a sheet-form substrate by thermally transferring the dye, so that the first re-transfer recording method has problems in that registration of the image is difficult and in that it is not always easy to handle the dye receiving layer supporting sheet in an apparatus. Therefore, a second re-transfer recording method has been proposed as a method which can solve those problems caused by the dye receiving layer supporting sheet.
The second re-transfer recording method is a method wherein an intermediate record support (a medium which temporarily keeps the dye receiving layer during recording (or printing)) is used which forms a closed loop such as a drum or a belt (e.g., an endless belt). The method in which the drum is used is disclosed in Japanese Patent Kokai Publication No.4-156384 and the method in which the belt is used is disclosed in Japanese Patent Kokai Publication No.8-67016. In this method, a dye receiving layer transferer (a medium which carries a dye layer to be transferred (moved) to the intermediate record support) is heated while being pressed, so that first, the dye receiving layer is transferred onto the intermediate record support from the dye receiving layer transferee. Seconds the dye is thermal transferred to the transferred dye receiving layer from a dye transferer such as an ink sheet, so that an image is formed. Last, the dye receiving layer on which the image has been formed on the intermediate record support is re-transferred to a (final) image receiver such as paper, i.e., in this method, the image is re-transferred. The second re-transfer recording method does not cause the problems which are caused in the first re-transfer recording method, since the dye receiving layer supporting sheet is not directly used so as to form the image.
When the method in which the drum is used as the intermediate record support forming the closed loop (the method disclosed in Japanese Patent Kokai Publication No.4-156384) is employed in the second re-transfer recording method, the intermediate record support can move speedily and with stability. However, when the dye receiving layer on which the image has been recorded is re-transferred to the final image receiver in the method in which the drum is used, the dye receiving layer, such as paper, should be heated from its back surface (i.e., a surface which is opposite to a surface with which the drum contacts) or a drum as the intermediate record support should be heated. Therefore, it is difficult to control the heat upon re-transferring the dye receiving layer on which the image has been recorded to the image receiver, so that there is a problem in that it is difficult to re-transfer with stability.
In contrast, when the method in which the belt is used as the intermediate record support forming the closed loop (the method disclosed in Japanese Patent Kokai Publication No.8-67016) is employed, a heating roller or a halogen lamp can be provided inside the belt which forms the closed loop as a heating source so as to re-transfer the dye receiving layer, on which the image has been formed, to the image receiver. Therefore, since the dye receiving layer on which the image has been recorded can be re-transferred by heating the belt and not by heating the image receiver, it can be relatively easy to control heat for re-transferring. However, it is difficult to control meandering of the belt, so that there is a problem in that speedy and stable thermal transfer of the recording image is difficult. Particularly, the belt as the intermediate record support moves is an unstable fashion. Since the image receiving layer is transferred onto such a belt and the image is thermal transfer recorded on the dye receiving layer on such a belt, it is conceived that versatility of the second re-transfer recording method may be reduced. Further, the halogen lamp, etc. is used as the heating source inside the belt. Therefore, it is conceived that since it is difficult to control a temperature of the surface of the belt, the versatility of the second re-transfer recording method may be reduced.
The present invention has been completed in order to solve the above problems. An object of the present invention is to provide a novel thermal transfer recording apparatus (such as a thermal transfer printer) for thermal transfer recording and a novel thermal transfer recording method (such as a thermal transfer printing method) which alleviate or substantially solve at least one of the problems in that a recording speed of an image is low, a stability of recording is poor, and a running cost of recording is high when the thermal transfer recording is carried out while recording a glossy and high quality image preferably in a digital mode. The thermal transfer recording method of the present invention is preferably carried out by using the thermal transfer recording apparatus of the present invention.
In an aspect of the present invention, a novel thermal transfer recording apparatus is provided, which comprises:
an intermediate record support which forms a closed loop and extends over a plurality of drums which are placed separately,
a dye receiving layer transfer section having a dye receiving layer transfer head which faces to a part of the intermediate record support on an outer periphery of one drum of the plurality of the drums,
an image recording section having at least one image recording head which faces to a part of the intermediate record support on the outer periphery of the one drum, and
an image transfer section having an image transfer head which faces to the intermediate record support inside of the closed loop.
According to the present invention, the intermediate record support extends over the plurality of the drums (for example, two or more drums) which are placed separately so as to form the closed loop. Therefore, a portion of the outer periphery of each of the plurality of the drums spaced separately contacts with a portion of the intermediate record support (which corresponds to the above parts of the intermediate record support). That is, each of the portions of the intermediate record support is positioned around each of such portions of the peripheries. As to the drum on which the part of the intermediate record support is positioned while the image recording head faces the intermediate record support, the intermediate record support is positioned around, preferably, not less than half of the whole outer periphery and, more preferably, not less than two thirds of the whole outer periphery of the drum.
The xe2x80x9cdye receiving layer transfer sectionxe2x80x9d herein is a region in which a dye receiving layer is transferred to the intermediate record support by heating a dye receiving layer transferee. More concretely, in the xe2x80x9cdye receiving layer transfer sectionxe2x80x9d, the dye receiving layer transferer is heated by the image receiving layer transfer head while being pressed to and contacted with the intermediate record support, so that the dye receiving layer of which its adhesive property has been enhanced moves from the dye receiving layer transferer to the intermediate record support.
The xe2x80x9cimage recording sectionxe2x80x9d is a region in which a dye tranferer is heated and a dye is thermally transferred to the dye receiving layer which has been transferred onto the intermediate record support, so that an image is formed on the dye receiving layer. More concretely, in the xe2x80x9cimage recording sectionxe2x80x9d, the dye transferer is heated by the image recording head while being pressed to and contacted with the dye receiving layer which has been transferred onto the intermediate record support, so that the dye moves from the dye transferer to the dye receiving layer (i.e., the dye thermally transfers) and the image is formed through the thermal transfer recording. It is noted that the xe2x80x9cdye transfererxe2x80x9d is a medium which includes a dye layer containing the dye to form the image.
The xe2x80x9cimage transfer sectionxe2x80x9d is a region in which the intermediate record support is heated, so that the dye receiving layer on which the image has been recorded is re-transferred to an image receiver. More concretely, in the xe2x80x9cimage transfer sectionxe2x80x9d, the dye receiving layer on which the image has been formed is heated by the image transfer head while being pressed to and contacted with the image receiver, so that the dye receiving layer of which its adhesive property has been enhanced is transferred to the image receiver. It is noted that the xe2x80x9cimage receiverxe2x80x9d can be said to be a xe2x80x9cfinal image receiverxe2x80x9d.
In the thermal transfer recording apparatus of the present invention, by driving at least one drum of the plurality of the drums which are placed separately, the intermediate record support which constructs the closed loop moves and circulates along the closed loop which is formed by the outer peripheries of the plurality of the drums. The dye receiving layer transfer section, the image recording section and the image transfer section are arranged in series in the listed sequence along the moving (or running) direction of the intermediate record support.
When a term xe2x80x9cupper reach (or upstream)xe2x80x9d or a term xe2x80x9clower reach (or downstream)xe2x80x9d is used in the present specification, those terms are based on the moving direction of the intermediate record support. Therefore, a direction from which the intermediate record support comes is called xe2x80x9cupper reachxe2x80x9d, and a direction toward which the intermediate record support goes is called xe2x80x9clower reachxe2x80x9d. Thus, in the thermal transfer recording apparatus of the present invention, the dye receiving layer transfer section, the image recording section and the image transfer section are arranged in such a listed sequence from the upper reach to the lower reach.
Furthermore, in the present specification, when a term xe2x80x9ctransferxe2x80x9d is used, the xe2x80x9ctransferxe2x80x9d means that the dye receiving layer of the dye receiving layer transferer is moved to the intermediate record support by heating the dye receiving layer transferee.
Further, the xe2x80x9cthermal transferxe2x80x9d or the xe2x80x9cthermal transfer recordingxe2x80x9d means that the dye transferer (or dye thermal transferer) is heated, so that the dye is moved to the dye receiving layer on the intermediate record support, whereby the image is formed (recorded or printed) on the dye receiving layer.
In addition, the xe2x80x9cre-transferxe2x80x9d means that the dye receiving layer on which the image has been recorded is heated, so that the dye receiving layer moves from the intermediate record support to the (final) image receiver.
In a further aspect of the present invention, a thermal transfer recording method is provided. The method of the present invention is characterized in that it comprises:
a dye receiving layer transfer step in which the dye receiving layer is transferred onto the intermediate record support by heating a back surface of the dye receiving layer transferer in the dye receiving layer transfer section,
an image recording step in which the dye is transferred to the dye receiving layer on the intermediate record support by heating a back surface of the dye transferer in the image recording section, so that the image is thermal transfer recorded, and
an image transfer step in which the dye receiving layer on which the image has been recorded is re-transferred to the (final) image receiver by heating a back surface of the intermediate record support in the image transfer section.
The dye receiving layer transfer step is carried out by using the dye receiving layer transfer head which is placed so as to face (a part of) the intermediate record support which is located on the drum and forms the closed loop. The image recording step is carried out by using the image recording head which is placed so as to face (a part of) the intermediate record support which is positioned on the drum and forms the closed loop. Moreover, the image transfer step is carried out by using the image transfer head which is placed in the inside of the closed loop. The method is carried out, preferably, by using the apparatus such as a thermal transfer recording apparatus according to the present invention as described above.
More concretely, the method of the present invention is carried out as follows.
In the dye receiving layer transfer step, the dye receiving layer transferer which provides the dye receiving layer is supplied from a source thereof, and the dye receiving layer is heated by the dye receiving layer transfer head while being pressed to the intermediate record support, so that the dye receiving layer becomes in a condition of adhering to the intermediate record support. Then, the dye receiving layer and the intermediate record support are cooled together while being maintained integrally. Thereafter, the image receiving layer transferer is separated from the intermediate record support, and preferably separated at an angle not smaller than a given angle, so that the dye receiving layer alone is left on the intermediate record support, and thereby the dye receiving layer is transferred to the intermediate record support.
In the image recording step, the dye transferer which provides the dye layer is supplied from a source thereof, and the dye layer is heated by the image recording head while being pressed to the dye receiving layer on the intermediate record support, so that the dye contained in the dye layer moves to the dye receiving layer on the intermediate record support and the image to be formed by the dye is printed. Then the dye transferer and the intermediate record support are cooled together while being maintained integrally. Thereafter, the dye transferer is separated from the intermediate record support, so that the image receiving layer alone is left on the intermediate record support, and thereby the image is formed. An image is formed by using a next dye in a method similar to the above described method on the dye receiving layer which already has the image formed as described above, when an image is formed by using a plurality of dyes in sequence.
In the image transfer step, the image receiver is supplied from a source thereof, the image receiver is heated by the image transfer head while being pressed to the image receiving layer on the intermediate record support, so that the dye receiving layer on the intermediate record support attaches to the image receiver. Then, the image receiver and the intermediate record support are cooled together while maintained integrally. Then, the intermediate record support is separated from the image receiver, so that the dye receiving layer is left on the image receiver and thereby the image is re-transferred on the image receiver.
In a further aspect of the present invention, the intermediate record support which is used for the thermal transfer recording apparatus or thermal transfer recording method as described above is provided.
Both of the dye receiving layer transfer head and the image recording head face to the intermediate record support on the outer periphery of the drum from the outside of the closed loop and the image transfer head faces the intermediate record support from the inside of the closed loop. As a result thereof, as to recording the glossy and high quality image, the present invention provides the thermal transfer recording apparatus and the thermal transfer recording method which alleviate at least one of the problems in that the thermal recording speed of the image is low, the stability of the recording is poor, and the running cost of the recording is high.